Over the years, internal combustion engines have evolved into more efficient and powerful machines. As part of this evolution, the structures, dynamics, and control systems of modern engines have become highly specialized at burning either gasoline or diesel fuel. Although this evolution has made engines more efficient and has often resulted in modest power increases, the resulting engine designs have proven to be difficult to modify for specialty purposes using conventional modification techniques and devices. There is a need to provide new modification devices and methods that may be used with modern engine designs. In particular, there is a need to provide new ways to adapt engines to operate using additional combustion reactants, such as nitrous oxide, and to operate using alternative fuels, such as propane, alcohol, hydrogen, compressed natural gas (CNG), liquid natural gas (LNG), and the like.
Nitrous oxide injection systems are used as performance enhancers to increase the power output of engines. Nitrous oxide injection systems generally operate by introducing a supply of nitrous oxide into the combustion chamber of an internal combustion engine, such as common two-stroke, four-stroke, diesel and Wankel rotary engines, which may be naturally aspirated or have forced air induction. Nitrous oxide contains about 36% by weight of oxygen whereas air contains only about 21% by weight of oxygen. The additional oxygen provided by the nitrous oxide when combined with an additional amount of fuel increases the power output of the engine relative to a similar engine using only air and fuel as the combustion reactants. Historically, such systems have been used in various applications. Currently, nitrous oxide systems are used in drag racing cars, trucks, motorcycles, snowmobiles, personal watercraft and street vehicles.
Modern nitrous oxide systems may be used with carbureted and fuel injected engines. There are two types of nitrous oxide injection system: “wet” systems and “dry” systems. Wet nitrous oxide injection systems meter (supply) both nitrous oxide and fuel to the engine, whereas dry nitrous oxide injection systems meter only nitrous oxide to the engine. Dry systems are used mainly in fuel injected engines, and the fuel for a dry system is typically provided by the engine's original fuel injectors or replacement injectors that may provide a different fuel flow rate than the original injectors.
Until recently, nitrous oxide injection systems were typically installed to provide nitrous oxide at a central location corresponding to the carburetor or throttle body of the engine. Carbureted engines and single-point fuel injected (SPFI) engines typically have a single fuel supply or set of fuel supplies located in a central location along the engine air inlet path. The inlet air in such engines typically passes through a filter, then through a carburetor (or throttle body, in the case of SPFI engines) where fuel is introduced into the airflow to create a fuel/air mixture. The intake plenums and runners on carbureted and SPFI engines are typically designed to convey air and fluid to the cylinders. Typically, each runner carries the fuel and air mixture to a respective cylinder of the engine. The runners are shaped and connected to the plenum to assure the delivery of an equal and homogeneous air fuel mixture to each cylinder. The fuel/air mixture is divided by the intake plenum (also known as an intake manifold) into several different airflows that feed the various engine cylinders. The intake plenum is designed to evenly distribute the fuel and air mixture to each cylinder. In such systems, the nitrous oxide may be supplied centrally much like the fuel, because the intake plenum will evenly distribute it to the cylinders along with the conventional fuel/air mixture. High HP engine applications use fogger nozzles to assure even fuel and nitrous oxide distribution to each of the cylinders. These fogger nozzles carry and mix the nitrous oxide and fuel stream into the induced air stream of the cylinder during the engine induction process.
In recent years, however, engine emissions standards have become stricter, and engine manufacturers have responded by producing multipoint fuel injection systems for almost all modern vehicles. Multipoint fuel injection systems use individual fuel injector nozzles located near each cylinder of the engine. Air is provided to each cylinder by a highly tuned intake plenum. Although multipoint fuel injection systems increase the combustion efficiency of the engine, and provide the potential for increased power, they have increased the difficulty of installing a nitrous oxide system on the engine. The problem stems largely from the “dry” intake plenums used with multipoint fuel injected engines. Dry intake plenums are designed to convey air, and not liquids, from the engine air inlet to the cylinders. As such, when nitrous oxide and fuel are supplied at a central location along the air inlet as they are with carbureted engines and single-point fuel injected engines, the fuel may not be evenly distributed to the cylinders by the dry intake plenums. Such condition causes some cylinders to run excessively rich and others excessively lean resulting in backfires in the intake manifold and/or engine failure. Other problems may also exist when using a single source of nitrous oxide with a modern multipoint fuel injected engine.
In order to accommodate the proliferation of multipoint fuel injected engines, nitrous oxide system manufacturers have provided systems that introduce nitrous oxide in the proximity of the cylinders. Prior art nitrous injectors use a nitrous oxide spray nozzle located near each cylinder's fuel injector. This solution, however, has several limitations. Two of the more problematic factors are the intake plenum thickness and intake plenum material. Current nitrous oxide systems for multipoint fuel injected engines are attached to the intake plenum by drilling and tapping threads into a hole in the engine's intake plenum (which are typically aluminum, but may be other materials, such as plastic or a combination of materials) and threading the nozzle into the plenum. Even under the best of circumstances, that is, when the intake plenum is aluminum and thick enough to engage a threaded fastener, the installation process is labor intensive and requires removal of the intake plenum to avoid contaminating the engine with debris created during the installation. This solution may not be used if the intake plenum is either too thin or made from a material that does not lend itself to accepting threaded fasteners, such as plastic. If the plenum is too thin or made of a weaker material such as plastic, then a boss must be welded, ultrasonically bonded or glued to the plenum at each spray nozzle location to allow the installation, and the intake plenum still must be removed to prevent contamination of the engine. The increased use of plastic and combined plastic and aluminum intake plenums has made these additional steps more often necessary. In addition, plastic plenums are more susceptible to damage during a backfire when they have been drilled and reinforced with a boss.
Other problems may also be present when attempting to use a conventional nitrous oxide system with a modern multipoint fuel injected engine. For example, the nitrous oxide spray nozzle must almost certainly be placed in a location that is not ideal for injecting fuel into the combustion chamber due to the fact that the original fuel injector is likely already in such a location. In addition, it may be difficult or impossible to locate the spray nozzle in a position that is ideal for combining the nitrous oxide with the fuel and air or for directing the nitrous oxide towards the cylinder intake because of space limitations within the engine compartment and because the intake plenum may be covered or otherwise obstructed by other engine components at the place where it is desired to locate the spray nozzle. These spray nozzles also have the tendency to project into the runner of the intake manifold restricting the air flow and thus reducing the volumetric efficiency of the engine. This is especially true for relatively small engines, such as those in motorcycles, snowmobiles and personal watercraft.
In addition to the above noted problems with modifying modern engines to use nitrous oxide, modern engine designs pose similar problems to those wishing to modify them to operate using alternative fuels. Alternative fuel vehicles use fuels other than those derived from petroleum products, such as: propane, alcohol, hydrogen, blends of alcohol and other fuels, compressed natural gas, liquid natural gas, and the like.
It would be desirable to provide an apparatus that can provide other fuels and reactants to the engine. For example, it may be desired to supply air to increase injector spray atomization, re-circulated exhaust gases to reduce exhaust emissions, or propane or compressed natural gas to enhance engine combustion efficiency and/or cold starting. It may also be desirable to provide alcohol, nitromethane, and diesel fuels to the engine.